The present invention relates to a watchcase and more particularly to a non-round portable watchcase having a simple and rigid joint construction between the case body and a back cover or the case body and a bezel, as well as a simple water resistant construction in applying the above mentioned joint construction.
FIGS. 1a-b, show typical non-water resistant watch construction of the conventional type. FIG. 1(a) shows a basic non-water resistant watch construction wherein a glass 5 is adhered to a case body 1 with a face A by adhesives, and joint recesses 1a which join to a back cover 4 are provided inside an inner circumferential wall 1c of the case body 1. Numeral 2 is a support member which is respectively provided with a flange 2b which extends internally so as to hold a movement 7 at an upper inner diameter of the case body and projections 2a (referred to hereinafter as peripheral beads) at a side wall 2f thereof. The support member 2 is united in one body with the back cover 4 at a lower peripheral edge 2g by brazing and the like, or the support member 2 can be made in one body with the back cover 4 if desired.
The support member 2 of the non-water resistant watch construction shown in FIG. 1(b) is the same as that of FIG. 1(a) functionally and in order to increase the design variety, a bezel 6 is adhered to the case body 1 with an upper face B and a glass 5 is adhered to the bezel 6 with the face A. To obtain a water resistant watch construction, in FIG. 1(c) an annular stepped portion 1b is provided at the contact surface of the case body 1 and the back cover 4 in order to interpose a gasket 8 therebetween so as to prevent the penetration of water therethrough. A watch construction corresponding to that shown in FIG. 1(c) is described, for example, in U.S. Pat. No. 3,714,775. By way of another method to hold the gasket 8, the annular stepped portion 1b can be provided at the back cover 4. As for the above construction, since the gasket 8 must be compressed in the vertical direction (axial direction of the case) of the back cover 4 and the case body 1, a sufficient compressive force could not be obtained if the joining force of the peripheral beads was weak and the number of manufacturing process steps were increased by providing the stepped portion at the case body 1.
Further, since the gasket 8 was wound around the external periphery of the support member 2 when assembled, the gasket 8 couldn't be stably held and assembly was troublesome. Therefore, various kinds of devices have been conventionally contrived as shown in FIGS. 2a-c in order to hold the gasket stably. Namely, since the round back cover can be entirely machined by a lathe, a gasket holding recess E1 can be machined by a lathe all around the internal periphery of the gasket as shown in FIG. 2(a). This type prior art construction is shown in Swiss Pat. No. 315,164. On the contrary, if the back cover is not round, a gasket holding recess E2 is machined by a deformation cutting machine and a milling machine all around the external periphery of the support member as shown in FIG. 2(b), or a gasket holding recess E3 similar to the gasket holding recess E2 shown in FIG. 2(b) is machined only at the corner portions of a non-round support member which can be lathed circularly as shown in FIG. 2(c).
However, in the case of the non-round back cover, the number of manufacturing process steps increased and the gasket could not be completely held. Moreover, as mentioned above, conventionally a round annular bezel is fixed to the case body by joining the joint engaging portion machined by a lathe to the case body, while as for a non-round bezel, the bezel 6 is united to the case body 1 by adhesives, caulking and the like as shown in FIG. 1(b). Accordingly, since the bezel 6 is fixed to the case body 1 and cannot be joined thereto and removed therefrom, the movement 7 is assembled from the back cover side after removing the back cover 4. The construction shown in FIG. 1(b) has been applied widely to various designs and is highly regarded. However, since the movement is assembled from the back cover side, movements and dials having a larger external diameter than the back cover 4 cannot be assembled and resultantly watch design has been restricted.
As shown in FIGS. 3a and 3b, the conventional peripheral beads were deformed in various ways by utilizing the relative strength between the case body 1 and the support member 2. In the case wherein the plate thickness w of the case body 1 was comparatively thin as shown in FIG. 3(a), the case body was deformed extending in the external diametrical direction and the case body 1 and the support member 2 were joined as shown in FIG. 3(a), and in the case wherein the plate thickness w of the case body was thick and hard to be deformed, the support member 2 was deformed in the internal diametrical direction as indicated by an arrow and the case body 1 and the support member 2 were joined as shown in FIG. 3(b). However, the conventional joint construction taking advantage of the deformation in the diametrical direction is attended with various disadvantages.
In FIG. 3(a), since the case body 1 is extended in the external diametrical direction at the back cover side, an action to separate the glass holding face (A in FIG. 1) from the glass 5 is applied thereto by the principles of the lever. As the result, the glass 5 and the glass holding face are separated in the case when the adhesion thereof was weak, or the glass 5 was chipped off in the case when the adhesion thereof was strong and the glass 5 was thin and weak in strength.
In the case wherein the case body 1 is not deformed as shown in FIG. 3(b), the support member 2 is deformed in the internal diametrical direction, and the flange 2b falls and clamps the movement at the portion C in the drawing and thereby the movement 7 is badly stressed.
If the support member 2 is strengthened so as not to be deformed, the peripheral beads 2a chip off since both the case body 1 and the support member 2 can't be deformed, and as a result the required joint can't be ensured.
As illustrated above, the conventional joint construction taking advantage of the deformation in the diametrical direction seems to be very simple, actually however, very strict controls over the glass adhesion, the receiving diameter of the movement, the shape of the peripheral beads, the plate thickness of the case body and the support member and the like have been required.